Using the "Save As" Feature to Create Design Templates
Ever want to reuse a template, but don't want to lose the previous one? Selecting the Save As button will open the design in a new tab and you can rename the design and use it again! This will also allow you to create different versions of the design, such as multiple sizes, or multiple colors, etc.
To resize the newly saved design, go into your Info tab > Design Settings and change the width and height for the design. You will then need to select all the layers on the canvas and resize them to fit the new artboard size.
Please note that it is recommended to first make a copy of the design with the Save As button and then make any changes you may want for the new design.